Rotating electric machine

Abstract

To control torque of a stator in a rotary electric machine having the stator and a rotor each of which is rotatable.SOLUTION: An electric motor 1 (rotary electric machine) comprises: a main motor 10 having a rotor 12 and a stator 13 each of which is rotatably provided; and an auxiliary motor 20 having an auxiliary stator 23 and an auxiliary rotor 22 relatively rotatable to the auxiliary stator. The auxiliary rotor 22 of the auxiliary motor 20 and the stator 13 of the main motor 10 are coupled with each other to be integrally rotatable.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rotating electrical machine.

Background Art

[0002] In a rotating electrical machine used as an electric motor or a generator, it is common practice to fix a stator to a housing or the like on the stationary side, and fix a rotor to a rotating shaft.

[0003] Patent Document 1 listed below discloses a rotating electrical machine (electric motor) capable of high output by making a stator and a rotor each rotatable and using the rotational force of the stator for the rotation of the rotor. Specifically, when decelerating the rotation of the rotor, the rotational force of the rotor is used to rotate the stator, and when accelerating the rotation of the rotor again, the rotational force of the stator is added to the rotational force from the drive current to rotate the rotor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0005] In the above rotating electrical machine, the stator is accelerated or decelerated by being magnetically coupled with the rotor, but the torque thereof cannot be controlled, and the stator rotates in an unregulated manner. Therefore, the torque of the stator may be excessive when restarting the rotor, and in this case, excessive torque is input to the rotor due to the magnetic coupling between the stator and the rotor, resulting in a large torque loss of the rotor caused by induced voltage.

[0006] Accordingly, the problem to be solved by the present invention is to prevent problems such as an increase in the torque loss of the rotor by making it possible to control the torque of the stator in a rotating electrical machine in which the stator and the rotor are each made rotatable. [Means for solving the problem]

[0007] To solve the aforementioned problems, the present invention provides a main rotating electric machine having a rotor and a stator that are rotatably mounted, and an auxiliary rotating electric machine having an auxiliary stator and an auxiliary rotor that is rotatable relative to it. The present invention provides a rotating electric machine in which the auxiliary rotor of the auxiliary rotating electric machine and the stator of the main rotating electric machine are connected so as to be able to rotate together as a single unit.

[0008] This rotating electric machine allows the torque of the stator of the main rotating electric machine, which previously rotated haphazardly, to be controlled by the auxiliary rotating electric machine. In other words, by driving the auxiliary rotating electric machine, it is possible to reduce the torque by decelerating the rotation of the stator, or to increase the torque by accelerating the rotation of the stator, regardless of the rotation of the rotor.

[0009] The above-described rotating electric machine may have a cylindrical housing that accommodates a main rotating electric machine and an auxiliary rotating electric machine. By housing the main rotating electric machine and the auxiliary rotating electric machine in a common housing in this way, the entire rotating electric machine can be made more compact. [Effects of the Invention]

[0010] As described above, according to the present invention, in a rotating electric machine having a rotatable stator and rotor, the torque of the stator can be controlled, thereby avoiding problems such as an increase in rotor torque loss. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing an electric motor according to one embodiment of the present invention. [Figure 2] This graph shows the time variation of the rotational speed of the rotor (solid line) and stator (dash-dot line) of the main motor. [Figure 3] This is a schematic cross-sectional view showing an electric motor according to another embodiment of the present invention. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0013] Figure 1 shows an electric motor 1 as a rotating electric machine according to one embodiment of the present invention. This electric motor 1 mainly comprises a main motor 10 as a main rotating electric machine, an auxiliary motor 20 as an auxiliary rotating electric machine, and a control unit 30 that controls them.

[0014] The main motor 10 includes an output shaft 11, a rotor 12, a stator 13, and a housing 14. The rotor 12 is fixed to the outer circumference of the output shaft 11 and has a plurality of magnets 12a arranged at equal intervals in the circumferential direction. The stator 13 has a stator core fixed to the inner circumference of a cylindrical (e.g., cylindrical) housing 14 and a coil wound around the stator core. The main motor 10 in this embodiment is a so-called radial gap type, in which the rotor 12 and the stator 13 face each other with a small radial gap between them. Alternatively, the main motor 10 may be a so-called axial gap type, in which the rotor and stator face each other with a small axial gap between them.

[0015] The rotor 12 and stator 13 are each rotatable independently. In this embodiment, the output shaft 11 is attached to the housing 14 via bearings 15 and 16. The output shaft 11 protrudes from the housing 14 in one axial direction (to the right in Figure 1), and this protruding portion is attached to the stationary body 42 via bearing 41. That is, the output shaft 11 and rotor 12 are rotatable relative to the stationary body 42, and the housing 14 and stator 13 are rotatable relative to the output shaft 11.

[0016] The coils of the stator 13 are electrically connected to the control unit 30 via known power transmission means such as brushes. The main motor 10 is provided with a reverse rotation prevention means that allows rotation of the housing 14 and stator 13 in the forward direction, but restricts rotation in the reverse direction.

[0017] The auxiliary motor 20 includes a rotating shaft 21, an auxiliary rotor 22, an auxiliary stator 23, and a housing 24. The auxiliary rotor 22 is fixed to the outer circumference of the rotating shaft 21 and has a plurality of magnets 22a arranged at equal intervals in the circumferential direction. The auxiliary stator 23 has a stator core fixed to the inner circumference of a cylindrical (e.g., cylindrical) housing 24 and coils wound around the stator core. The coils of the auxiliary stator 23 are electrically connected to the control unit 30. The auxiliary motor 20 in this embodiment is a so-called radial gap type, in which the auxiliary rotor 22 and the auxiliary stator 23 face each other with a small radial gap between them. Alternatively, the auxiliary motor 20 may be a so-called axial gap type, in which the rotor and stator face each other with a small axial gap between them.

[0018] The auxiliary rotor 22 is rotatable relative to the auxiliary stator 23. In this embodiment, the housing 24 and the auxiliary stator 23 are fixed to a stationary body 43, and the rotating shaft 21 is attached to the housing 24 via bearings 25 and 26. The rotating shaft 21 protrudes from the housing 24 in one axial direction, and its tip is fixed to the housing 14 of the main motor 10. That is, the auxiliary stator 23 and the housing 24 are the fixed side, and relative to them, the auxiliary rotor 22, the rotating shaft 21, and the housing 14 of the main motor 10 are rotatable as a single unit.

[0019] The electric motor 1 includes a rotation sensor 51 that detects the rotation of the rotor 12 of the main motor 10, and a rotation sensor 52 that detects the rotation of the stator 13 of the main motor 10. The rotation sensors 51 and 52 detect the rotation speed, rotation angle, or both of the detection target (rotor 12, stator 13). As rotation sensors 51 and 52, known contact type sensors, optical type sensors, magnetic type sensors, etc., can be used. In this embodiment, the rotation sensors 51 and 52 detect the rotation of the output shaft 11 and the housing 14 by non-contact detection of a plurality of sensor targets provided on the outer circumferential surface of the output shaft 11 or the housing 14. The rotation sensors 51 and 52 are electrically connected to the control unit 30, and detection signals from the rotation sensors 51 and 52 are sent to the control unit 30.

[0020] Instead of the rotation sensor 52 that detects the rotation of the stator 13, a rotation sensor (for example, an electromagnetic induction type sensor) that detects the relative rotational speed between the stator 13 and the rotor 12 may be provided. From the relative rotation angle and rotational speed between the stator 13 and the rotor 12 detected by this rotation sensor, and the rotation angle and rotational speed of the rotor 12 detected by the rotation sensor 51, the rotation angle and rotational speed of the stator 13 can be calculated.

[0021] Hereinafter, a driving method of the electric motor 1 will be described. The solid line in FIG. 2 shows the temporal change in the rotational speed of the rotor 12 and the output shaft 11, and the one-dot chain line in FIG. 2 shows the temporal change in the rotational speed of the stator 13 and the housing 14.

[0022] First, the control unit 30 energizes the coil of the stator 13 of the main motor 10, thereby integrally rotating the rotor 12 and the output shaft 11 in the forward direction. At this time, a force that rotates in the reverse direction acts on the stator 13 and the housing 14, but the rotation of these in the reverse direction is restricted by the reverse rotation prevention means. In this way, with the stator 13 and the housing 14 stopped, the rotor 12 and the output shaft 11 are accelerated in the forward direction (time t0 to t1), and when reaching a predetermined speed, they are rotated at a constant speed (time t1 to t2).

[0023] Then, when decelerating the output shaft 11, the rotational energy of the output shaft 11 is transmitted to the stator 13 to rotate the stator 13 and the housing 14 in the forward direction. Specifically, the coil of the stator 13 is energized to generate an excitation force that tends to rotate the rotor 12 in the reverse direction relative to the stator 13. As a result, the rotor 12 and the output shaft 11 are decelerated, and the stator 13 rotates in the forward direction due to the reaction of the force that decelerates them (time t2 to t3). At this time, the housing 14, the rotating shaft 21 of the auxiliary motor 20 fixed thereto, and the auxiliary rotor 22 rotate integrally with the stator 13. At this time, the auxiliary stator 23 of the auxiliary motor 20 is not energized.

[0024] When the output shaft 11 stops, the power supply to the coils of the stator 13 is stopped, causing the stator 13 to continue rotating in the forward direction at a nearly constant speed due to inertia (times t3 to t4). Alternatively, the power supply to the coils of the stator 13 may be continued even after the output shaft 11 has stopped to further accelerate the stator 13. In this case, it is preferable to restrict the rotation of the output shaft 11 in the reverse direction so that the output shaft 11 does not rotate in the reverse direction due to the reaction force of the force that rotates the stator 13. In addition, the power supply to the stator 13 may be stopped before the output shaft 11 stops.

[0025] While the stator 13 is rotating due to inertia, the auxiliary motor 20 adjusts the rotational speed of the stator 13 and housing 14 to a predetermined value ω1. Specifically, the rotation sensor 52 detects the rotational speed of the stator 13 and housing 14, and if this rotational speed is greater than the predetermined value ω1, that is, if the torque of the stator 13 and housing 14 is excessive, the auxiliary stator 23 of the auxiliary motor 20 is energized to generate an excitation force that decelerates the auxiliary rotor 22, thereby decelerating the auxiliary rotor 22 and the rotating shaft 21, housing 14, and stator 13 connected thereto until the rotational speed becomes ω1 (see P in Figure 2). At this time, the rotation of the auxiliary rotor 22 may generate electricity in the auxiliary stator 23 and store this electricity in a battery.

[0026] On the other hand, if the rotational speed of the stator 13 and housing 14 is less than ω1, the auxiliary stator 23 of the auxiliary motor 20 is energized to generate an excitation force that accelerates the auxiliary rotor 22, thereby accelerating the auxiliary rotor 22 and the rotating shaft 21, housing 14, and stator 13 connected thereto until the rotational speed becomes ω1 (see Q in Figure 2). In this way, by accelerating and decelerating the stator 13 and housing 14 of the main motor 10 with the auxiliary motor 20, the rotational speed of the stator 13 and housing 14 is maintained at a predetermined value ω1.

[0027] Subsequently, when the output shaft 11 is rotated again, the stator 13 is energized again to rotate the rotor 12 in the positive direction relative to the stator 13 (times t4-t5). As a result, in addition to the excitation force between the stator 13 and the rotor 12, the rotational force (inertial force) of the stator 13 and the housing 14 is also applied to the rotor 12, increasing the energy that rotates the rotor 12 and the output shaft 11. In other words, it is possible to reduce the amount of electricity supplied to the stator 13 while maintaining the torque input to the rotor 12 and the output shaft 11, thereby saving energy.

[0028] As described above, when restarting by magnetically coupling the rotor 12 with the stator 13, if the rotational speed (torque) of the stator 13 is excessive, an excessive torque is suddenly input to the rotor 12, generating a large induced voltage, which increases the torque loss of the rotor 12. In this embodiment, as described above, by adjusting the rotational speed of the stator 13 to an appropriate value (ω1) with the auxiliary motor 20, an appropriate amount of torque is input to the rotor 12, thereby preventing an increase in the torque loss of the rotor 12.

[0029] The present invention is not limited to the embodiments described above. Other embodiments of the present invention will be described below, but redundant explanations of points similar to those described above will be omitted.

[0030] The electric motor 1 shown in Figure 3 differs from the above embodiment in that the main motor 10 and the auxiliary motor 20 are housed in a common housing 60. In the illustrated example, of the cylindrical (e.g., cylindrical) housing 60, one axial side (right side in the figure) is the first part 61 that houses the main motor 10, and the other axial side (left side in the figure) is the second part 62 that houses the auxiliary motor 20. By housing the main motor 10 and the auxiliary motor 20 in a common housing 60 in this way, the entire electric motor 1 can be made more compact.

[0031] Specifically, in the electric motor 1 shown in Figure 3, the stator 13 of the main motor 10 is fixed to the inner circumferential surface of the first portion 61 of the housing 60, and the rotor 12 is arranged on its inner circumference. An auxiliary rotor 22 is provided in the second portion 62 of the housing 60. In the illustrated example, a magnet 22a is embedded in the second portion 62 of the housing 60, and this portion functions as the auxiliary rotor 22. Alternatively, an auxiliary rotor 22 having a magnet 22a may be fixed to the inner circumference of the second portion 62 of the housing 60. An auxiliary stator 23 is arranged on the inner circumference of the auxiliary rotor 22, and the auxiliary stator 23 is fixed to a fixed body 43. In the illustrated example, the axial end (left side in the figure) of the output shaft 11 of the main motor 10 is inserted into the inner circumference of the fixed body 43 and is rotatably supported via bearings 44 and 45.

[0032] In the embodiment shown in Figure 3, since the main motor 10 and the auxiliary motor 20 are arranged in close proximity in the axial direction, it is preferable to provide a magnetic shielding means 63 between them in the axial direction. As the magnetic shielding means 63, for example, a plate or film made of a material that does not conduct magnetism can be used. By providing the magnetic shielding means 63 in this way, it is possible to prevent the magnetism of the main motor 10 from affecting the auxiliary motor 20, or conversely, the magnetism of the auxiliary motor 20 from affecting the main motor 10.

[0033] In the embodiments described above, the electric motor 1 is shown as an electric motor that rotates the output shaft 11 using electricity. However, it is not limited to this, and the output shaft 11 can also be used as an input shaft, and the motor can be used as a generator that generates electricity using the rotational force input to this input shaft. [Explanation of Symbols]

[0034] 1. Electric motor (rotating electric machine) 10. Main motor (main rotating electric machine) 11 Output shaft 12 rotors 13 status 14 Housing 20. Auxiliary motor (auxiliary rotating electric machine) 21 Rotation axis 22 Auxiliary rotors 23 Auxiliary Stator 24 Housing 30 Control Unit 42,43 Fixed body 51, 52 Rotation sensor 60 Housing

Claims

1. The system comprises a main rotating electric machine having a rotor and a stator that are rotatably mounted, and an auxiliary rotating electric machine having an auxiliary stator and an auxiliary rotor that is rotatable relative to it. The main rotating electric machine has a reverse rotation prevention means that allows rotation of the stator in the forward direction but restricts rotation in the reverse direction. The auxiliary rotor of the auxiliary rotating electric machine and the stator of the main rotating electric machine are connected so as to be able to rotate together as a single unit. A rotating electric machine in which, when the rotor is rotated in the forward direction from a state in which the stator and rotor of the main rotating electric machine are stopped, the rotation of the stator in the reverse direction is restricted by the reverse rotation prevention means, thereby stopping the stator.

2. The rotating electric machine according to claim 1, having a cylindrical housing for housing the main rotating electric machine and the auxiliary rotating electric machine.

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